I want to reuse the same tilemap object in multiple layouts with multiple tile configurations and upload the image for the tilemap only once. I could use the json expressions, save those, and then load them in game but I was hoping to be able to see the different configurations in the editor as well. Does that make sense?

I've been wondering this as well.In the mean time, I've just separated my tilemaps into smaller images and planned my areas around what tilemaps will be used for certain layers. It's certainly less efficient that way though, and more time consuming.

Yeah, I work around it by placing it in, downloading the json version of it changed, and then on each layout I "load from json" for the different version... it works, but it's not efficient from my standpoint.